It is a conventional practice to cool beer kegs and barrel-shaped containers of drinkable liquids by immersing at least the bottom portion of the keg in an open container filled with ice. Another type of portable cooler apparatus, such as shown in U.S. Pat. No. 3,443,397 to Donovan et al or U.S. Pat. No. 3,614,875 to McCallun, has an inner container or liner open at the top for receiving a barrel therein and an outer container joined to but spaced from the inner container for filling ice around the inner container. In U.S. Pat. No 4,514,993 to Johnson, a sleeve-type cooler apparatus is formed as a cylindrical jacket with an open bottom for slipping over a barrel and a plurality of vertically seamed pockets for holding ice and the like to cool the barrel.
The conventional devices mentioned above have the following problems and disadvantages. Since beer kegs and refreshment barrels often have their spigots at the lower portion near the bottom of the keg, they cannot be immersed in ice in an open container above the height of the spigot, thereby limiting the amount of ice that can be placed in cooling contact around the keg. With the open-top double walled container, the keg must be lowered into the inner liner, which precludes use of kegs with lower spigots as well as risks damage to or tearing of the liner.
In the sleeve-type cylindrical jacket having internal pockets, the requirement that the ice be filled in the pockets reduces its effectiveness in cooling the barrel since the ice cannot be directly packed around the sides of the barrel. Such seamed jacket coolers are also relatively expensive to fabricate and are susceptible to tearing, leaking, and weakening over time.